roundabouts (rab) and channelized turning lanes (ctl) dona sauerburger, coms november 16, 2012...

Outline of workshopOutline of workshop

What are features of RABs and CTLs?What are features of RABs and CTLs? How to recognize RABs and CTLs?How to recognize RABs and CTLs? TasksTasks

Locating crosswalkLocating crosswalk Aligning and maintaining alignmentAligning and maintaining alignment Determining when to crossDetermining when to cross

Learning to recognize Situations of Learning to recognize Situations of UncertaintyUncertainty

Practice /experiencePractice /experience Brainstorm / problem-solve tasksBrainstorm / problem-solve tasks

Features of RABs and Features of RABs and CTLsCTLs

Roundabouts: An Informational Guide (NCHRP Report 672)Roundabouts: An Informational Guide (NCHRP Report 672) http://safety.fhwa.dot.gov/intersection/roundabouts/fhwasa10006/

Features of RoundaboutsFeatures of Roundabouts

NOT mini-roundabouts or large traffic circles!NOT mini-roundabouts or large traffic circles!

Circular vehicular pathway (counterclockwise)Circular vehicular pathway (counterclockwise) Splitter islandsSplitter islands Crosswalks set back from “intersecting street”Crosswalks set back from “intersecting street” Drivers entering RAB yield to traffic in the circleDrivers entering RAB yield to traffic in the circle No stop sign or signalNo stop sign or signal

Important:Important: How many lanes?How many lanes? Turning radius?Turning radius?

Channelized Turning Channelized Turning LanesLanes

““Porkchop island;” “Channelized lane”Porkchop island;” “Channelized lane”

ExceptionsExceptions

Upstream/downstreamUpstream/downstream

Features of CTLsFeatures of CTLs

Usually:Usually: UncontrolledUncontrolled Single laneSingle lane ““Upstream” traffic yields to Upstream” traffic yields to

“downstream” traffic “downstream” traffic Crosswalk at centerCrosswalk at center

USUALLY!USUALLY!


Two lanesTwo lanes


Stop sign!Stop sign!

Considerations for CTLConsiderations for CTL

IMPORTANT: does it have a:IMPORTANT: does it have a: deceleration lane?deceleration lane? acceleration lane?acceleration lane?

IMPORTANT: is the turning radius IMPORTANT: is the turning radius Narrow? (slower vehicles) orNarrow? (slower vehicles) or wide? (drivers can go faster)wide? (drivers can go faster)

No acceleraton/delerationNo acceleraton/deleration Acceleration lane Acceleration lane

Deceleration laneDeceleration lane Deceleration Deceleration andand accelerationacceleration

Turning radiusTurning radius

Wide radiusWide radius

Narrow radiusNarrow radius

OK, now the nitty-gritty!OK, now the nitty-gritty!

TASKS for the blind traveler:TASKS for the blind traveler: Recognize RAB or Right-turn-laneRecognize RAB or Right-turn-lane Find crosswalkFind crosswalk AlignAlign Determine when to start crossingDetermine when to start crossing Maintain alignment / recover from Maintain alignment / recover from

veerveer

TASK #1:TASK #1:

Recognizing RAB or CTLRecognizing RAB or CTL

RAB: What might you RAB: What might you notice?notice?

Traffic approaching and leaving roundabout Traffic approaching and leaving roundabout seem to be split at the island (making the seem to be split at the island (making the shape of a “Y” with leg)shape of a “Y” with leg)

NO consistent pattern!! NO consistent pattern!! some vehicles don’t slow down, others on the some vehicles don’t slow down, others on the

same street slow down and proceed, some stop same street slow down and proceed, some stop and wait;and wait;

no turn-taking like at a signal.no turn-taking like at a signal. Perpendicular traffic not unusual except:Perpendicular traffic not unusual except:

Only can hear traffic going to the right, andOnly can hear traffic going to the right, and Can sometimes hear muffled traffic going to the Can sometimes hear muffled traffic going to the

leftleft At some RABs, approaching traffic seems to At some RABs, approaching traffic seems to

turn right but then continues straightturn right but then continues straight Splitter island may make street sound widerSplitter island may make street sound wider

Task #2: Find crosswalkTask #2: Find crosswalkAssuming there is one!Assuming there is one!

What is a crosswalk? What is a crosswalk? (Marked/unmarked)(Marked/unmarked)

Varies from state to stateVaries from state to state Usually “extended pedestrian path”Usually “extended pedestrian path” Sometimes “corner to corner”Sometimes “corner to corner” Sometimes “extended ped path from Sometimes “extended ped path from

BOTH directions”BOTH directions”

Find crosswalkFind crosswalkAssuming there is one!Assuming there is one!

Find crosswalk at Roundabout? Find crosswalk at Roundabout? (from notes)(from notes) Not predictable!Not predictable! Shoreline on curb side (either along Shoreline on curb side (either along

your approach or go to the circle and your approach or go to the circle and turn around and look).turn around and look).

Listen to people (they are likely to be Listen to people (they are likely to be at the crosswalk)at the crosswalk)

Curb cuts are likely to be in Curb cuts are likely to be in crosswalk especially at roundaboutscrosswalk especially at roundabouts

Find crosswalkFind crosswalkAssuming there is one!Assuming there is one!

Find crosswalk at Right-turn lane? Find crosswalk at Right-turn lane? (from notes)(from notes)

Shoreline along street to find curb cutShoreline along street to find curb cut Crosswalk is often between upstream and Crosswalk is often between upstream and

downstream but sometimes along the downstream downstream but sometimes along the downstream streetstreet

Crossing at downstream (with no acceleration lane)Crossing at downstream (with no acceleration lane) AdvantagesAdvantages

Drivers are already slowing down or stopping to yield to trafficDrivers are already slowing down or stopping to yield to traffic recovery from veer may be easierrecovery from veer may be easier

DISadvantagesDISadvantages drivers are looking toward the traffic, away from you, drivers are looking toward the traffic, away from you, andand are are

not expecting younot expecting you!!!!!! if that is not where the crosswalk is, you don’t have the right if that is not where the crosswalk is, you don’t have the right

of wayof way

Align! (?)Align! (?)

At Roundabout At Roundabout (from notes)(from notes)

Cut-through for splitter island may Cut-through for splitter island may not straightnot straight

Maybe align with perpendicular Maybe align with perpendicular traffic (but be aware it may already traffic (but be aware it may already be turning)be turning)

Use individual features that you know Use individual features that you know are straight at that intersection are straight at that intersection (“back-up strategy”)(“back-up strategy”)


At Separate right-turn-lane At Separate right-turn-lane

no reliable solutionsno reliable solutions(Previous workshop participants had no solutions!)(Previous workshop participants had no solutions!)

Listen to waiting vehicles and aim to Listen to waiting vehicles and aim to the front of them – reliable???the front of them – reliable???

Can you rely on direction of curb cut?Can you rely on direction of curb cut?

reliable???reliable???


At Separate right-turn-lane At Separate right-turn-lane (NOT from notes – no solutions!)(NOT from notes – no solutions!)

Listen to waiting vehicles and aim to Listen to waiting vehicles and aim to the front of them IS NOT RELIABLE.the front of them IS NOT RELIABLE.

Can you rely on direction of curb cut?Can you rely on direction of curb cut? NO – NOT RELIABLENO – NOT RELIABLE

Reliable “back-up” strategy: Reliable “back-up” strategy: Use individual features that you know Use individual features that you know

are straight / fixed at that intersectionare straight / fixed at that intersection

Maintain alignmentMaintain alignment

ROUNDABOUT ROUNDABOUT (from notes)(from notes)

Use veer-reduction strategies such as Use veer-reduction strategies such as crossing quicklycrossing quickly

Use sound of perpendicular traffic in the far Use sound of perpendicular traffic in the far lanelane

Use any permanent sound features that Use any permanent sound features that may exist to walk toward or along may exist to walk toward or along

Use tactual clues in crosswalk if they existUse tactual clues in crosswalk if they exist Use slope of ground in the street while Use slope of ground in the street while

crossing.crossing.HOW TO CORRECT A VEER:HOW TO CORRECT A VEER: Not usually a problemNot usually a problem

Maintain alignmentMaintain alignmentCHANNELIZED TURNING LANE: CHANNELIZED TURNING LANE: (from notes)(from notes)

Use sound of locator tone if it is on islandUse sound of locator tone if it is on island Listen to where the cars are waiting at upstream street Listen to where the cars are waiting at upstream street

and walk toward the front of them (and walk toward the front of them (if the stopbar is at if the stopbar is at the cornerthe corner) )

HOW TO CORRECT A VEER (missed island)HOW TO CORRECT A VEER (missed island) Develop skill of being able to hear vehicles pass and then Develop skill of being able to hear vehicles pass and then

know when you’ve reached the lane where they were (this know when you’ve reached the lane where they were (this skill REQUIRES TRAINING). Then:skill REQUIRES TRAINING). Then: listen to the traffic on the other side of island to determine listen to the traffic on the other side of island to determine

how far away it is. how far away it is. When you cross, if you walk far enough to have reached When you cross, if you walk far enough to have reached

where they were, you know when you’ve gone too far! where they were, you know when you’ve gone too far! When you determine you’ve missed the island because When you determine you’ve missed the island because

you’ve walked too far and haven’t reached ityou’ve walked too far and haven’t reached it turn around 180 degrees and go back toward the curb where turn around 180 degrees and go back toward the curb where

you started ORyou started OR if you feel the street sloping, follow the slope down because it if you feel the street sloping, follow the slope down because it

goes to a gutter and curb.goes to a gutter and curb.

Determine when to start Determine when to start crosscross

No stop sign or traffic signal, SONo stop sign or traffic signal, SO

There are only 3 conditions for There are only 3 conditions for crossing:crossing:

Gap in traffic long enoughGap in traffic long enough Vehicles are there but they yieldedVehicles are there but they yielded Trust that Trust that ifif there is a vehicle there is a vehicle

coming,coming,

driver will yielddriver will yield

Determine when / whetherDetermine when / whetherto crossto cross

No rulesNo rules ! ! ! ! ! ! Consider advantages / disadvantages Consider advantages / disadvantages

(what are the risks) and how to deal with (what are the risks) and how to deal with disadvantages (decrease risk)disadvantages (decrease risk)

Make decisions about crossing based on:Make decisions about crossing based on:ACCEPTABLE RISK!ACCEPTABLE RISK!

Choices:Choices: CROSS because risk is acceptable – use:CROSS because risk is acceptable – use:

Gap in trafficGap in traffic Yielding vehiclesYielding vehicles Trust drivers to yieldTrust drivers to yield

DON’T CROSS because risk is NOT acceptableDON’T CROSS because risk is NOT acceptable use alternatives use alternatives


Cross During Gap in TrafficCross During Gap in Traffic(ASSUMING YOU HAVE GAPS IN (ASSUMING YOU HAVE GAPS IN

TRAFFIC LONG ENOUGH!)TRAFFIC LONG ENOUGH!)

Skill neededSkill needed:: Recognize whether Recognize whether you have enough warning you have enough warning

(“Situation of Confidence”)(“Situation of Confidence”)OROR you can’t hear/see far enough for warningyou can’t hear/see far enough for warning

(“Situation of Uncertainty”)(“Situation of Uncertainty”)

Situations of uncertaintySituations of uncertainty


Cross During Gap in TrafficCross During Gap in Traffic(ASSUMING YOU HAVE GAPS IN TRAFFIC LONG ENOUGH!)(ASSUMING YOU HAVE GAPS IN TRAFFIC LONG ENOUGH!)

Skill neededSkill needed:: Recognize whether Recognize whether you have enough warning you have enough warning

(“Situation of Confidence”)(“Situation of Confidence”) you can’t hear/see far enough for warningyou can’t hear/see far enough for warning

(“Situation of Uncertainty”)(“Situation of Uncertainty”)

Traveler needs to:Traveler needs to: Determine width of streetDetermine width of street Understand (intuitively) own crossing timeUnderstand (intuitively) own crossing time Recognize when not long enough warningRecognize when not long enough warning

Train participants to recognize Situation of Train participants to recognize Situation of Uncertainty/Confidence Uncertainty/Confidence 41:0041:00

Situation of Uncertainty?Situation of Uncertainty?

What to do?What to do?

Analyze risk!Analyze risk! Do you have the right of way?Do you have the right of way? How likely are you to be surprised?How likely are you to be surprised? If you are, how likely is it that will it stop If you are, how likely is it that will it stop

for you?for you? If it doesn’t stop for you, how likely is it If it doesn’t stop for you, how likely is it

that you will be seriously injured or killed?that you will be seriously injured or killed?Practice analyzing risk of situation Practice analyzing risk of situation 35:2235:22


Cross When Drivers Have YieldedCross When Drivers Have Yielded

Skill neededSkill needed:: Confirm Confirm allall drivers drivers stopped stopped

Ideas to get drivers to stop: Ideas to get drivers to stop: 32:29; 35:2232:29; 35:22

Ideas to confirm yield?Ideas to confirm yield? ETAETA Provoke honk Provoke honk (hold up sign / cup ear)(hold up sign / cup ear)


TRUST That Drivers Will YieldTRUST That Drivers Will Yield

Analyze likelihood that drivers will Analyze likelihood that drivers will yield.yield.

HAWKS (now called PHBs) and raised crosswalks were tested in the HAWKS (now called PHBs) and raised crosswalks were tested in the 3-78 3-78 project and the PHBs were tested at that Michigan roundabout.project and the PHBs were tested at that Michigan roundabout.

http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_674.pdfandandhttp://www.rcocweb.org/Lists/Publications/Attachments/126/HAWK%20Final%20Report%202011.pdf

But the short version is that where tested, they improved access for But the short version is that where tested, they improved access for blind peds. PHBs basically pedestrian pushbuttons and APS and walk blind peds. PHBs basically pedestrian pushbuttons and APS and walk indications as part of the setup; still have to be aware of potential indications as part of the setup; still have to be aware of potential red light running, etc. Raised crosswalks just seemed to really slow red light running, etc. Raised crosswalks just seemed to really slow down the cars, and make them more aware of the potential for down the cars, and make them more aware of the potential for pedestrians? I'm not sure; there was still the potential for multiple pedestrians? I'm not sure; there was still the potential for multiple threat (that second lane) but somehow it just calmed things down threat (that second lane) but somehow it just calmed things down enough enough that they all stopped.that they all stopped.Basically the Michigan installations were a result of an ADA complaint Basically the Michigan installations were a result of an ADA complaint

and they are now installing PHBs at all their multilane roundabouts.and they are now installing PHBs at all their multilane roundabouts.

roundabouts (rab) and channelized turning lanes (ctl) dona sauerburger, coms november 16, 2012...

Documents

ctls slide

acceleration slide

exceptions slide

ctl slide

veer slide

faster slide

signal slide

narrow radius slide